Note
The HA-20 was released just a few months after the HX-30 six meter transmitter, and was designed specifically to give the HX-30 a little more punch. The HA-20 looks like a miniature version of the HA-10.
The amplifier uses a pair of 6146 tubes in push-pull to produce 125 watts input PEP SSB or about 75 watts on AM, and requires from 2.5 to 10 watts of drive. The built-in power supply is solid state, but uses an OA2 regulator.
The amplifier features forced-air cooling, extensive shielding, a multi-function meter, a 50Ω tuned grid input, a link-coupled output, and stub neutralized finals. The output circuit matches 50-75Ω antennas.
Front panel controls include coupling, loading, tune, power on/off, meter function, band, and meter adjust. There also is a pilot light on the front panel. The meter reads grid and plate current, plate voltage, and relative power. The HA-20’s panel meter is unique in that it is the only one to use a black face with a white scale prior to the introduction of the SB series.
There is a rear panel control for bias adjustment. The rear panel includes SO-239 connectors for RF input and output and a ground post.
The HA-20 is enclosed in a one-piece copper clad steel cabinet and is painted in two-tone green to match HX-30, TX-1, etc.
Beware the fused power plug.
References:
Review. Electric Radio. Dec 2016.
Drive power: 2.5 to 10 watts PEP
Maximum power input:
SSB: 125 watts PEP
AM: 75 watts
Power output: 70 watts PEP
Output impedance: 50 to 75Ω
Output coupling: link
Input impedance: about 50Ω
Input coupling: link (tuned grid)
Frequency coverage: 49.8 to 54 MHz
Power supply:
filament: 6.3 volts @ 4 amps
spare: 6.3 volts @ 4 amps
bias: –150 VDC
plate: 600 VDC
Power requirements: 120 VAC, 50/60 Hz, 95 watts standby, 200 watts at full output
Tubes: (1) 0A2, (2) 6146A.
Photos, general information and specifications from "Heathkit: A Guide to the Amateur Radio Products," by Chuck Penson, WA7ZZE. Used with permission.
